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Client Error on MultiPart request

mglettigmglettig Switzerland

We are doing a multi part request. The embedded device running mongoose OS is setup as a webserver. The connection is secure (SSL).

We trigger the mutlipart request from the client using curl.

When testing the multi part request using the curl script we get every once in a while the following error in curl: "curl: (56) SSL read: error:00000000:lib(0):func(0):reason(0), errno 10054"

We traced the traffic using Wireshark. There we saw that every time the error occurred the client (curl) closed the connection with a TCP package containing the RST flag (without a FIN package before).

Mongoose OS version: master @ eea6b7514a20f68c116fa1c827e71b86ff97a03c (v1.2++).
MCU: ESP8266

We observed the same issue when the client is an iOS App instead of the CURL script. Therefore something must be wrong in the embedded device.

Any ideas of what the problem might be? Any ideas of how to further debug the problem? Could I tune the lwIP settings somehow?

One idea was that the embedded device might be to slow to process all the packets. But TCP flow control is supposed to handle this scenario, right?

Best regards,


  • SergeySergey Dublin, Ireland

    Hi Michael,

    please mos config-set debug.level=3 debug.mbedtls_level=3

    Then reproduce the problem, and publish the respective logs (pastebin is a good way).

  • mglettigmglettig Switzerland

    Hi Sergey

    I sent you a PM containing the logs. The logs revealed that the MCU crashed. I could not yet figure out why it crashed. It looks like the crash occurs when I want to send a http reply to my client.

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